1. Field of the Invention
The present invention relates to an image recording device, and particularly to an image recording device suitable for recording images by exposing, for each color, color photosensitive materials having spectral sensitivity in the visible region.
2. Description of the Related Art
In a full-color image recording device in which light beams emitted from a light source are externally modulated by using a one- or two-dimensional light shutter array, a white lamp such as a tungsten lamp has been conventionally used as the light source. However, in the image recording device in which a white lamp is used as the light source and the light shutter array is used as an external modulation element, the following problems arise: (1) white lamps have low luminous efficiency and cannot obtain the amount of light required to expose color photosensitive materials; (2) due to short life span, white lamps need to be frequently replaced and are therefore inconvenient; and (3) when a white lamp is used, color separation needs to be carried out by using a color wheel or the like having filters of R, G, and B, and since a rotating mechanism for mechanically rotating the color wheel is necessary, the device becomes large, and it takes time to switch the filters.
An organic electroluminescence element in which a fluorescent organic material is used for a light-emitting layer is referred to as an organic EL element. Organic EL elements have advantages over other light emitting elements in that they are easy to manufacture, small and lightweight. Recently, there have been obtained high-quality organic electroluminescence elements which are as good as light emitting diodes (LEDs) formed of inorganic materials in terms of emission intensity, luminous efficiency, durability, and the like. Therefore, application of high-quality organic electroluminescence elements to exposure heads for exposing photosensitive materials such as silver halide photosensitive materials has been studied. For example, an optical recording device, which includes an optical writing unit having an array of organic EL elements for the respective R, G, and B, is suggested in Japanese Patent Application Laid-Open (JP-A) No. 7-22649. Since the array of organic EL elements for the respective R, G, and B is used in this device, color separation by filters and a rotating mechanism such as a color wheel are not necessary.
In the image recording device described in JP-A No. 7-22649, the array of organic EL elements used as the light source is directly modulated in accordance with image signals. However, since the organic EL elements form a diffusion light source, a problem arises in that direct modulation of the organic EL elements results in optical crosstalk. Further, the array of the organic EL elements is usually laminated on a common substrate, and therefore, thermal crosstalk is also generated.